Process of detinning.



F. van KU'GBLGBN & G. 0. SBWARD. PROCESS OF DETINNING.

' APPLIOATIOH FILED APB.22 1909. 1,086,921. Patented Feb. 10, 191i 4 SHEETS-SHEET 1.

WITNESSES:

F. VON KUGBLGEN' & e. 0. SEWARD.

PROCESS OF DET INNI-NG. AYPLIOATIOH FILED APLQB. 1909.

1,986,921. I Patented Feb. 10, 191 1 4 SHEETS-SHEET 3.

INVENTORS: "-14 QM;

By Alto wl NESSES:

meys, I

- STATES PATENT OFFICE.

FRANZ v6! KI TGELGEN, F HOLCODIBS ROCK, VIRGINIA, AND GEORGE O. SE'WARD, OF

EAST ORANGE, NEW J ERSEY, ASEIGNOBS, BY MESNE ASSIGNMENTS, TO COLUMBIA- KNICKERBOCKEB TRUST COMPANY, Till/STE E, A CORPORATION OF NEW YORK.

OF DETINNING.

Patented Feb. 10, 191.4.

Applicflttidn filed April 22, 1809. Serial No. 491,599.

' Bedfm-d and State of Virginia, and GBOBGE Sn'wann, a citizen of the United States, residing at East ()mmge, in the county of Essex and Nate of New Jersey, have jointly hm'entied (main new and useful Impromlomemts in Processes of Oetinnin'g, of which the following is a -r-rpeci1icaiimn ihis isn'enbion relates to the rletinning of ton scrap or amber tin bearing material by t'reatin'g it in a closed tank with dry chloriai gas, the operatirm being conducted at a temperature mrfiiciently low to PIQVGIIl the 1T(IIl of the cup being attacked by the drhwrin. This process is set forth and claimed in our a plim'timm Seriai No. 189,272. filed. Jami am 1'6. 1904- (being Lmers Patent- No.

m'mza, granted March a, mac).

m qn'actisnag this zmoresfi it not newssaior essential that the chloriu gas shall he of full strength, it being admissible to i-rse i-t "with a mmsirlciable admixture of air,

(this being the annual condition of the chlorin as obtained from the dleapest 'iwailah'le mums, namel yflthe eleotmlytic tanks or cells in which any dhlorin. such as oonnmm salt,

is being elecitmlyzed.

The process is preferably practised in a WWII-l0! not forth in Letters Patent No. s 853.461, granted May 14, 11907, that is to my, by 'first passing dry (*AllllOflll through 85 the --(,l etinnin=g vessel or tank wzhil-e suitably oonhrol'liing the temperature; then rcmowing the Htannic o'h'lorid which adheres to the residual iron scrap by passing :hloi'infiha'ough the vessel in)! a sufficient 40 time: and finally displacing the olrlm in from the vessel by passing :a current dry air o-r other inert gas (such as nitrogen) through the vessel. After flhis "last operation has continued long enough to remove '46 all l but a trace of chlorin, the vessel may be safely opened for the removal of the :det'mncd iron or black scrap, and iior :recharging a. with tcin scrap.

According to our present invention we M) render 'fihe process practically continuous by employing a series of tanks 61' vessels which are connected to item a circuit and are uperated in succession. The operation isdivided up into suitable units of time, say for example of one hour or more each, depending upon the size of the tanks; the amennt of tin scrap therein, the Strength of the chlorin, and the. :rate of flow of the-chlorin. During each timeamit one of thetan'ks will ordinarily be cut out.0f the series, being opened for the removal-of the iron scrap and the reclmrging with tin scrap to be detinned. The :remainingtanks are .so 00nnerted that air is being admitted to the one which has been longest changed and the scrmp in which has been completely dc tinned; the next tank in the series receives fresh dry chlori-n gas togetherwith the air passing from the preceding tank and carrying the chlorin which it 'hasdispl-aced themfrom; in each successive tank the mixture of rhlorixn and air encounters 'a fresher or newer charge of tin scrap with the tin on which the chlcr'm combines to form stannic chiorid, until in the last tank of the series the ch-lcrin has all or practically all been 'riunovecl from the air, whereupon the air which remains is 1h-awn out by any slitable suction device such as a pump or egieomr. Thus the tank which is most newly charged with tin scrap is traversed first by air maintaining only a small residue of ch'lorin. which if the process is ideally conducted is wholly eliminated in this tank by rs-acting with the tin on the scrap thereih; at the end of the prescribed time-unit this tank is advanced one step in the series, and consequently receives a current of air containing a langerw proportion of chlorin, miherby the reaction between the chlorin' and tin proceeds more rapidly; at the end of each stintsunit the serial position-oi the tank is thus advanced, so that after-a suitable interval (depending upon the number of'banks m themes) the tank iniquestion is neceiivi-ng dhlorin at such strength that the maximum rapidity of reaction is attained; the,

next aerial advance of the tank will cr ma y occur aafite the detinning operation therein has been soll'y or substantially completed,

so that "I 1e it is receiving thexmixture meet rich chlcrim the effect 30f the latter wholly var chiefly to take sup i such aesidne 10f .etmnic '0 i adhering to the iron scrap, the treatment during this time-limit continuing suiticiently long totake up practically all of such residual chlor-id; at the next serial change the admission of chlorin is cut ofi" from the tank in question and shifted to the next following dank, so that the tank iu (ptestiou receives only a current of air (or any inert gas) which displaces the chlorin remaining inthe interstices-of the scrap. and thereby eliminates practically' all residual chlorin from the tank; at the next serial change the air admission is cut off and the tank is thus thrown out of the circuit, so that it. may be opened to remove the detinned iron scrap and recharge it with tin scrap. To facilitate these last operations the scrap is best placed in a wire or other foraminous cage or grating which can be conveniently lowered into or lifted out of the open top of the tank.

The tanks ma be of varying number, depending upon't e precise'method in which the successive operations are to be conducted. For the preferable succession of operations as just described there should be at least four tanks in order to provide for simultaneously (1) dctinning (-2) absorbing chlorid (3) displacing chlorin with air, and (4) removing the scrap and recharging. lut the number of tanks might be further diminished by sub-dividing the given timeunit so that for example operations .Nos. (3) and (4) might be performed successively in the. same tank during a given timeunit. Or the sequence of operations and the time-interval allotted to each might be otherwise varied accompanied by a corresponding variation in the number 0 the tanks and in the manipulation of their connections.

Figure 1 of the accompanying drawings is an elevation of an apparatus comprising a ljrattery of six tanks or vessels. These are shown on a small scale and by reason thereof no attempt is made to show the valves or other smaller details. Fig. 2 is an elevation showing the terminal tanks and parts of two intermediate tanks, with their connecting pipes and valves. Fig. 3 is a plan of the apparatus shown in Fig. 2. Figs. 4 and 5 are vertical cross sections-between thetanks; in F i'g. 4- the tank ispartly in section. Fig. 6 i a. diagrammatical elevation showing a rry of four tanks. Fig. 7 is a dianrammagical plan of the tanks shown in Fig. 6. l ng. 8 a plan of a modified arrangement.

Referring to the drawings let A A designote the respective tanks or detinning vessels. which are also consecutively numbered as l. 2. 3. etc. These tanks are here shown as upright cylindrical vessels with conical bottoms to facilitate draining oil' the liquid chlorid and with rcmmxablc tops or lids a. to facilitate introducing and emoving the Page B containing the scrap. The tanks are water jacketed to facilitate cooling thqn in case the heatof the reaction becomes execs sive. The construction is shown in Fig. 4- 'where the tank is partly broken away to show the construction in vertical section. In "this figure Ii is the inner shell constituting the wall of the tank proper and c is the outer shell forming between them the Water jacket (I. The connections for admitting water to and discharging it from the jackets are not shown. being well understood.

" .The several tanks are connected in a series" by means of suitable pipes which are pro vidcd with valves or st op-cocks for controlling the flow. Ideally the tanks.would be arranged in a circular series, each connecting to the next in an essentially endless arrangement; but in most situations it is more convenient to place the tanks in a straight row, and this is the arrangement shown in Figs. 1 to 5. This arrangement, however,' involves a somewhat more complicated arrangcme'nt of piping than would be required for the supposed circular series.

A pipe C leads from the bottom of each tank to the top of the next tank in the. series. These pipes make as direct a communication as possible but in the case of the last tank in the series (No. 6) the connection is completed through a horizontal return pipe I) which leads to the top-inlet of the first tank (No, 1). Two other horizontal pipes are provided, namely. a chlorin inlet pipe E and an outlet or suction pipe G. The pipes l) and G. where the) cross the vertical pipes (l C, connec with them through horizontal branches E F. and G 2 respec' tively. Each of the pipes C C consists ossentially of three parts. namely, a portion C extcndingtrom the bottom of ondtank up as far as its connection with the branch pipe (lr; an intermediate portion C between the branch pipe G and E; and an upper portion C leading from the pipe E to the top of the next tank. of cocks or valves may be provided for suit ably controlling the flow through these pipes, it being only necessary that provision be made for admitting the chlorin from the pipe E to the upper section C of one of the. connecting pipes, while cutting it oft from the lower sections of such pipe, and for connccting the suction pipe G to any one of the lowersections CK while cutting it off from the upper section, and for connecting together the three sections of any of the pipes C while cutting such pipe off from the pipes E and G. in addition each tank is provided with an air-inlet valve F. which is most conveniently connected with a lateral branch joining the upper section C ofcach oi the connecting pipes C. i.

The valves and pipe connections are most. clearly indicated in Fig. 4. In this view thrce- .\ay cocks r (I are shown at thcjuno Various arrangements 7 ti ons of the riser pipe C with the horizontal with the horizontal .iranch pipes; or, they may as shown be turned so that the intermedia-te section C is cut. off from communication from the u per and lower sections, the branch pipe E being connected through the cock 0 with the upper section C; and the bran'chpipe (ir being connected through the cock 9 with the lower section C In addition we have shown sto -cocks h h in the respective branch pipes and G, but these are not essential, although constituting a desirable recaution. An alternative arrangement of valves is shown in. Fig. 5, where instead of the three-way cocks three ordinary stop-cocks are used, namely, the cocks h It already referred to and a cock in the pipe section C, by a suitable a justment of these three cocks provision may be made for the same control of the flow as in Fig. 4. From the bottom of each tank lea'ds a drip pipe Hcontrolled by a s iitablevalve or coc i. The purpose of the pi e H is to drain off the liquid stannic t'lllOI'ltwhich collects in the bottom of the tank. The pipe H might be entirely distinct from the pipe (3, but for convenience a single pipe is used for both at the outlet from the tank, the pipe section (3 branching therefrom upwardly while the main pipe H extends downwardly. The several pipesll H are preferably connected all to one chlorid outlet by means of inclined drainage pipes l I. From the lowest point the chlorid outlet pipe J leads down to discharge into any suitable chlorid collecting vessel.

The operation may be "best show a battery of four tanks. In these figures in order to simplify the diagrams the return pipe I) is shown as carried behind the series of tanks. The several pipes and valves or cocks are shown as having the same letters as in the preceding figures, but to enable the relations .of the valves to be clearly seen they are in Fig. 7 placed side by side, the three-way cocks a being drawn as though located in horizontal portions of the pipes C. the particular adjustment of valves shown, tank No. 2 is cut out of series for recharging; air is entering through valve F into the 'top of tank No. 3 to displace the remaining chlorin therefrom; the air circulates downwardly through this tank and u through its pipe C to enter the top of tank R O. 4; at the same time chlorin is introduced through'pipe E into the same connecting. pipe C, between tanks Nos. 3 and 4, commingli'ng with the air at the three-way cock e thereof. The mixed 55 alr'and chlorm pass down through tank No.

understood from the diagrams, Figs. 6 and 7, which In these diagrams, and with chlorin, inorder to ta thereto, thereby drying the scrap; the mixed 'chlnrin and air, carrying stannic chlorid vapor, then pass from the bottom of tank No. 4 to the next tank in the series, which in the arrangement shown is tank No- I. To reach this tank they pass around through the connectionpipe I). (in entering tank No. l the chlorin encounters undetinncd scrap and proceeds to react with the tin thereon to form 'stannic ch lorid. the rate of admission of chlorin', considering theextent of its dilution with air, and by suitably cooling the vessel by circulation of water or other cooling fluid through the water jacket, the temperature is kept down below the point at which the chlori'n would attack the iron of the scrap. If any stannic chlorid is volatilized by the heat,'it is condensed within the vessel 11 on reaching cooler surfaces therein, either e surfaces of cooler portions of the scrap, where thereaction has not yetproceeded so far as to beat them above the boiling point of SnCl or the'cooled walls of the vessel. The stannio chlorid which drains from thc'scraps runs '4, which contains detinned scrap, the .ch1orin absorbs the stannic chlorid adhering By suitably limiting out. through the bottom outlet and the valve i being open it )asses out tl'irough the pipe H, and runs'ott through the )ipe I to tie ehlorid vessel. It the seri u included a larger number of tanks, the air carrying a small residue of chlorin and air would pass thence thrmigh one or more additional tanks containing fresh tin scrap, whereby the-last. residue of chlorin would be taken up by its reaction with the tin. of only four vessels shown in Figs. ti and 7, the chlorin-from tank No. 1 passes directly through pipe section C to the valve 9 and thence c t. through the/pipe G to the suction.

But with the series At the end of the prescribedtime-unit, the

tank No. 2 having been recharged with fresh scrap and closed, the several valves are. turned so as to isolate tank No. 3' from the active series, the airv bein then introduced first to tank No. 4, and t e chlorin to tank No. 1, in which the detinning operation is mainly eon-ducted. Tank No. 3 is then opened, the detinned iron scrap is removed therefrom, and it is recharged with fresh tin scrap. Thus the operation proceeds, one tank after another being emptied and recharged, and the successive operations being each time advanced from one tank to the next.

It is preferable to employ tanks enough so that the fresh tin scrap will first be spent or most dilute e up the last portion thereotand discharge only air to the suction; and so that in. each succeeding stage of the process this tank will be traversed bv successively stronger chlorin-until its scrap shall be pompletely detinned; after'which traversed by the nearly itcontinues to receive the strongest. ohlorin long enough to absorb substantially all the stannic chlorid and thorougl'lly dr the scrap; and after this it is traversed by a cur-- rent f air ft a suflicient time to displace substantially all the remaining chlorin. in order'that when the tank is opened there shall be no waste of chlorin. and the opera t-ives shall not be subjected to the risk of inhaling the suffocating fumes of either chlorin or stannic chlorid vapor.

The process and apparatus may be LJUH- siderably modified "ithin the limits of our invention. Such modifications will be apparent to mechanics and engineers constructing detinning apparatus for carrying out our process. As one example of such a modification weshow in Fig. 8 a plan of a circular series of tanks, their connecting pipes being shown in diagram in similar manner to Fig. 7. But instead of the pipes E and G being horizontal ipes traversing tlee series with a multiplicity of branches. they are here shown as upright pipes mount .ed upon a central turn table K and having each one branch. so that by turning the turn table they can be'swung to any desired position so that their ranches will connect witli the desi ed branches communitaiting withthe connecting pipes C. (1 between the tanks. Thus the chloriu enters through pipe IQ. is conducted through its branch pipe to the (foi ciding branch leading int the tank which is first to receive the chlorin; and from the last tank in the series the residual air passes into the branch connecting with the suction pipe G. The branch pipes pro- "ieeting from the pipes E and (l are provided with couplings which enable them to be united to the ends of the respective stationary branch pipes. By placing the branches of pipes E and G in difl'ereut hori zontal' planes. the liability oii arny mistake in making connections may be eliminated.

it is desirable to provide the apparatus with means for facilitating the. subsequent washing of the detinned scrap. The detin-, ning operation leaves upon the iron scrap a very thin coating of ferric chlorid. believed to be due to the union of the ehlorin with so much of the iron as had formed a superficial or intermediate alloy ith the tin beneath the coating proper thereof. If this adherent ferric chlorid were left. it would cause a rapid rusting of the iron, which would detract from its value for remelting. It is therefore important to wash off this ironchlorid. which is easily done. since this ehlorid is readilv soluble in water. For this purpose we provide a scimratc washing: tank or vat L shown itLFlQ. l which is uncovered and preferably arranged lower than the other tanks. \Vc also pro-- vide some convenient means; for lifting; the cage B out of any of the tanks A. andronveying it to the tank L, and. lowering it into the 'ilbll-\\3it.l therein. shown in Fig. 1. this means consists of a trolley M running upon an overhead track l. and carrying any suitable sort of wind lass or hoisting gear Q for lifting and l af ing the cage. For convenience an el' rated platform R is arr: ruled, in front of the r w of tanks.

We are awa re that in early efi'orts to iletin by chlorin pins, but without any revelation of temperati'ire, it was p :iposed two detinning tanks. chargin' ternation, and passing the a vapors from one into the oil. V air into the tank containing the detinncc scrap and thereby displacing the residual chlorin and the stannic chlorid exi ting a vapor into the other or newly charged tank. Our process differs from any heretofore proposed in that we employ sutlicient tanks to constitute a series through which the chlorin and air are circulated continuously in such manner as to admit of a constant inflow of chlorin and a constant outflow of air to the suction device. We are thus enabled to conveniently utilize electrolyticallyproduced chlorin which is taken directly from the electrolytic cells, and so ctmliuuously as to avoid necessity for storing any material bulk of the gas.

"0 usually prcfcr the useot' suction for circulating the chlorin and air. especially when drawing the chlorin from electrolytic cells. but in some instances it may be preferable to employ pressure to force the chlorin through. For example. we have success fully practised our invention by using lie cfied chlorin admitted at. a suitable KIIU from a flask or vessel containing it. that the pressure thus applied. to the t Moran forced it to circulate through the pipes. in such case it is necessary to apply means for introducin g air under pressure. at the valve if.

Our invention is to be disting" shed from the use of two detinning tanks into which the tin scrap and chiorin are introduced. in

in the construction alternation; and is to be distinguished from 2 those processes in which chlorin is circulated through tin scrap withoutany provision for suitably controlling the temperature.

\Ve claim as our invention:

1. The process of detinning which consists in circulating dry chlorin thritiugrh a succession of tanks containing tin sarrap in varying stages of detinningz while con trolling the temperature to keep it below that. at which the iron is attacked.

2. The process of detinning which consists in circulating dry chlorinjgas tl'irougl'i asuccssion of tanks containing tin scrap in varying stages of detinning. passing the gas first through the tank containing the scrap which is most: nearly detinncd. and th nee. through tanks containing; successively iresher .scra qhile controlling the tem-y below that at which the in circulating a mixture of dry chlorin gas and an inert gas.

(as ail), through a succesof tanks containing tin scrap inv vary- 7 ing stages of damning, while controlling the temperature to keep it below thatat which the iron is attacked.

4. The process of detinning which consists in'circulating a mixture of dry chlorin gas and an inert gas (as air), through a succession of tanks containing tin scra iii varying stages of detinn'ing, easing t e gaseous mixture first through -t e tank containing the scrap which; is most nearly detinned, and thence t rough tanks containing successively fresher scrap, and finally drawing ofi the residual inert gas.

The process of detinning'which consists in circulating dry chlorin gas through a succession'of tanks containing tin scrap in varying stages of de-timiing, so that a freshly char ed tank receives first thespent. or attenuate chlorin from preceding tanks, and receives subsequently stronger chlorin until the detinning 18 completed, and finally passing'an inert gasthrougli .the tank containing the deiinned scrap. R 6. The process of detinning which consists "in circulating a mixture of dry chlorin gas and an inert gas (as air) through a sucoes 'sion of tanks containing tin scrap in vary ing stages of detinning, and passing.- such inert gas through the tank containin the detinned scrap to displace the chlorin t erefrom, admittgng'fresh chlorin to mix with the inert gas" paseingfrom said tank, hnd passing such mixture thence into-the next tank of the series.

7 The process of detinning which consists in irculating a mixture of chlorin gas and an inert gas (as air) through a succession of tanks containing tin scrap in varying stages of detinning, by intr ucing such inert gas to the tank containing the detinned scrap, and admitting fresh tank, the inert gas admixing therewith and being circulated serially through the succes-- sive tanks. 8. The process of detinning by circulating chlorin gas through a succession of tanks containing tin scrap in varying stages of detiniiing, which consists in intr'oducingfan inert gas (as air) into the tank containing detinned scrap, and circulating t thence through the series of tanks, whi e 1I1tIOdllC- ing the chlorin to series, whereby it forms a mixture with the inert gas, and circulates therewith until the chlorin is removed therefrom by c0mbining with the tin.

9. The process of det-mning by circulating chlorin gas through a succession of tanks chlorid, and

'o eration in the chlorin to a subsequent a subsequent tank in the containing tin scrap invarying stages of detmning, which consists in introducing an inert gas (as air) into the tank containing the detinned scrap, and introducing the strongest chlorin into a subsequent tank also containing detinned scrap, mixing said gases and circulating them through the subsequent tanks containing fresher charges of (in scrap until the chlorin is removed by combining with the tin. D 10. The o'cess of detinning' which consists in circulating a mixture of dry chlorin gas and an inert gas (as air) through aimcces' sion of tanks containing tin scrap in vary ing stages of diet-inning, -crn'iducting the reaction at such temperature ,as to-retain in the tanks in ii uid form the resulting stannie revving off such thebottoins of the tanks.

11. The process of deti'nning by circulating I chlorin gas through a succession of tanks ing stages of said containing tin scrap in java detinning, which consists in cou lin tanks in se ies except for 'one tank wfiichis isolated fr such series, opening said tank, removing the with fresh scrap and again closing it while the detinning operation is proceeding in the remaining tanks, then coupling the newly charged tank into the series and isolating therefrom the next succeeding tank for rearging, up lying a suction each time to the outlet c the newly charged tank, adnittihg air; .to the tank longest charged with scrap, and admitting chlorinto a subsequent tank so that the chlorin and air may mix and be drawn together through the series oi tanks.

12. The method of detinning etin-scrap, which consists in establishin a series of separate charges to be treate star-tin the first charge by the a missioir'of chlorin gas diluted with air, decreasing the air mitted as the detinning in progresses, passing the gases charge successively throu h the other charges of the series as the etinning in the first charge proceeds, and finally passing the residual gases left after the completion of the detinning operation in the first said charge charge into one of the charges utilizing dilutdchlorin, substantially as described.

'13. The method which consists in establishing a series 0 separate charges to be treated,.starting the o eration in the first charge by the a sion of chlorin gas diluted :Wltltflll, creasing the air dilution of the gas thus admitted as the detinning in said charge progresses, passing the gases from the first charge successively throu h the other charges of the series 'as the etinning n the first charge proceeds, finishing the detmmng of the first-charge by concentrated chlorin,

liquid fromfrom the first detinned scrap, recharging dilution" of the gas thus pdof .detinning tin scrap,

and finally passing the residual gases left after the completi n 'of the detinning operation' in the first charge into one of the] charges utilizing dilute chlm'in, suhstan tially as described.

14. The method of detinning tin scrap, which consists in establishing a series of separate charges to be treated,,s tarting the operation in the first charge by the admission of chlorin gas diluted with'air; decreasing the air dilutigu of the gas thus admitted as the detinning in said charge progresses, passing the gases from the first charge successively through the ether charges of the series as the'detinning'in the first charge proceeds, and finally passing, by means of a diluting current of warm, dry air the residual gases left after the completion of the detinning operation in the first chawe into one of the charges utilizing dilute dhlorin, substantially as described.

In witness whereof, we have hereunto, signed our names in the presenceof two subscribing witnesses.

FRANZ VUN KUGELGEN. GEORGE U. SEVALD.

lVitnesses:

ALBERT VAN \VAIKLR, M. K. Blm'rrzcs. 

